The conventional integrated circuit device generally includes active components such as transistors and diodes in a chip, and passive components such as condensers and resistosr, conductive traces in/on a substrate. In SOC (system on chip) technology, all the active components and passive components are intended to be fabricated in high density on the active surface of a chip. However since the operative functions of integrated circuit device become complicated and various, SIP (system in package) solution becomes more practicable than SOC. Since the different material characteristics and manufacturing processes between active components and passive components (ordinarily active components are made by thin film wafer fabrication processes and passive components are made by thick film wafer fabrication processes), it is very difficult to manufacture embedded passive components inside an IC chip. Especially for the IC chip with RF (radio frequency) functions, the resistance of the embedded passive component in a chip cannot precisely control. The quality and yield of the IC chip is worse due to the embedded passive component inside the IC chip. As disclosed in R.O.C. Taiwan Patent No. 517,275, a passive component is embedded in an IC chip as part of the IC chip. The embedded passive component is formed on a void space of active surface of the IC chip free of bonding pads. Because the passive component is much cheaper than the IC chip and also is made by different wafer fabrication processes, a passive component embedded in IC chip will result in lower yield and higher fabrication cost.
Alternatively, a passive component is embedded in a package substrate as part of the substrate. As disclosed in R.O.C. Taiwan Patent No. 457,652, a BT substrate includes an embedded capacitor inside. In order to shorten the electrical path between an IC chip and an embedded capacitor, the IC chip is connected to the BT substrate by flip-chip connection, especially the IC chip with RF functions. However the BT substrate is made of BT resin which CTE is between 16×10−6 and 18×10−6(1/K), the CTE of the BT substrate does not match with the CTE (4×10−6(1/K)) of the IC chip. It is essential to provide an underfilling material between the IC chip and the BT substrate. Normally the embedded capacitor inside the BT substrate is made by a built-up process, that is to say, the embedded capacitor cannot be small in dimension nor formed in fine pitch.